This thesis provides design approaches for waveguide filter with prescribed transmission zeros. The emphasis is on a new class of filter, developed in recent years by utilizing non-resonating nodes (NRNs). First, a novel circuit model of the coupling irises of waveguide filters is developed in order to aid the design of waveguide filters with NRNs for relatively wide band applications. Also, analytical solutions of the circuit parameters are presented and verified by experimental design. Secondly, based on this new circuit model, a systematic approach for the design of filters with NRNs is developed and illustrated with two filters. The first has intermediate fractional bandwidth of 3.5%; Good results are obtained without performing global optimization. The second has a relatively wide fractional bandwidth of 8.33% and good results are achieved with very limited global optimization. The results are verified by EM simulations. Furthermore, for choosing an empty waveguide to realize the NRNs, some novel criteria are proposed to improve the spurious free window of the filter.

This thesis provides design approaches for waveguide filter with prescribed transmission zeros. The emphasis is on a new class of filter, developed in recent years by utilizing non-resonating nodes (NRNs). First, a novel circuit model of the coupling irises of waveguide filters is developed in order to aid the design of waveguide filters with NRNs for relatively wide band applications. Also, analytical solutions of the circuit parameters are presented and verified by experimental design. Secondly, based on this new circuit model, a systematic approach for the design of filters with NRNs is developed and illustrated with two filters. The first has intermediate fractional bandwidth of 3.5%; Good results are obtained without performing global optimization. The second has a relatively wide fractional bandwidth of 8.33% and good results are achieved with very limited global optimization. The results are verified by EM simulations. Furthermore, for choosing an empty waveguide to realize the NRNs, some novel criteria are proposed to improve the spurious free window of the filter.

In this thesis, a novel electronic ballast that includes a repeatedly resonating ignition circuit is proposed for metal halide lamps. The proposed electronic ballast features a two-stage structure that comprises a power factor corrector and a full-bridge inverter used for current control, filtering and ignition. The full-bridge inverter consists of a leg operating at low-frequency with unidirectional switches and a leg operating at high frequency with bidirectional switches. The low-frequency side performs repetitive resonating on the load circuit with inductors and capacitors to accumulate a high voltage for ignition. Adjusting the duty-ratio of the high-frequency side allows for the regulation of the lamp current. The inductors and capacitors in the load circuit function not only producing the high ignition voltage but also filtering out high-frequency components, so that to drive the lamp with a low-frequency square-wave current. The proposed electronic ballast employing the full-bridge inverter with the specially designed control scheme and circuit parameters allows the metal halide lamp to tackle the demanding starting transient and steady state operation. With a simpler circuit structure and a reduced component count, the product cost will be much lower.

Nesta dissertação estudamos sistemas de spins em redes de baixa dimensionalidade e em temperatura nula, analisando suas transições de fases quânticas. Mais precisamente, estu- damos as propriedades do estado fundamental e as possíveis transições de fase do modelo de Heisenberg quântico antiferromagnético de spin-1/2, com interações entre os primeiros e segundos vizinhos, em diversas redes, e em particular na rede triangular, que é o foco de nosso estudo. Para a obtenção do estado fundamental aproximado, usamos um método variacional em que a rede é particionada num conjunto de plaquetas de sítios. O estado fundamental é escrito como um produto tensorial dos estados das plaquetas. Para a rede triangular, escolhemos um triângulo como uma plaqueta. Quatro fases foram encontra- das: a fase antiferromagnética de Néel, a colinear, a fase de Néel modificada e aquela que denominamos de ligação covalente ressonante. Obtivemos as energias e as magnetizações de subrede em função da razão entre as interações de primeiros e segundos vizinhos. En- tre as fases de Néel e a colinear, podemos observar a fase de ligação covalente ressonante caracterizada como um singleto quanto ao spin de cada plaqueta. / In this thesis we study spin systems in low-dimensional lattices at zero temperature, analyzing their quantum phase transitions. More precisely, we study the properties of the ground state and the possible phase transitions in the antiferromagnetic spin-1/2 quan- tum Heisenberg model with interaction between the first and second neighbors, in several lattices, and in particular in the triangular lattice, which is the focus of our study. To obtain the approximate ground state, we use a variational method in which the lattice is partitioned into a set of plates of sites. The ground state is written as a tensor product of the states of plates. For the triangular lattice, we choose a triangle as a plate. Four phases were found: the antiferromagnetic Néel phase, the collinear, the modified Néel phase and that we call resonating valence bond. We obtained the energy and the magnetization as a function of the ratio of the interactions between the first and second neighbor sites. Between the Néel and collinear phases, we can observe the spin resonating valence bond phase, characterized as a singlet with respect to the spin of each plate.

Nesta dissertação estudamos sistemas de spins em redes de baixa dimensionalidade e em temperatura nula, analisando suas transições de fases quânticas. Mais precisamente, estu- damos as propriedades do estado fundamental e as possíveis transições de fase do modelo de Heisenberg quântico antiferromagnético de spin-1/2, com interações entre os primeiros e segundos vizinhos, em diversas redes, e em particular na rede triangular, que é o foco de nosso estudo. Para a obtenção do estado fundamental aproximado, usamos um método variacional em que a rede é particionada num conjunto de plaquetas de sítios. O estado fundamental é escrito como um produto tensorial dos estados das plaquetas. Para a rede triangular, escolhemos um triângulo como uma plaqueta. Quatro fases foram encontra- das: a fase antiferromagnética de Néel, a colinear, a fase de Néel modificada e aquela que denominamos de ligação covalente ressonante. Obtivemos as energias e as magnetizações de subrede em função da razão entre as interações de primeiros e segundos vizinhos. En- tre as fases de Néel e a colinear, podemos observar a fase de ligação covalente ressonante caracterizada como um singleto quanto ao spin de cada plaqueta. / In this thesis we study spin systems in low-dimensional lattices at zero temperature, analyzing their quantum phase transitions. More precisely, we study the properties of the ground state and the possible phase transitions in the antiferromagnetic spin-1/2 quan- tum Heisenberg model with interaction between the first and second neighbors, in several lattices, and in particular in the triangular lattice, which is the focus of our study. To obtain the approximate ground state, we use a variational method in which the lattice is partitioned into a set of plates of sites. The ground state is written as a tensor product of the states of plates. For the triangular lattice, we choose a triangle as a plate. Four phases were found: the antiferromagnetic Néel phase, the collinear, the modified Néel phase and that we call resonating valence bond. We obtained the energy and the magnetization as a function of the ratio of the interactions between the first and second neighbor sites. Between the Néel and collinear phases, we can observe the spin resonating valence bond phase, characterized as a singlet with respect to the spin of each plate.

L'enjeu du travail est d'apporter une preuve de concept d'une architecture simplifiée de spectromètre en utilisant comme détecteur un réseau ultra-dense de NEMS associés à des éléments de circuit CMOS afin d'amplifier le signal in situ et de les adresser individuellement. Depuis plusieurs années, l'équipe du professeur Roukes à CALTECH a présenté une démonstration de spectrométrie de masse avec un NEMS. En parallèle, le CEA/LETI-MINATEC a développé une approche de fabrication dite VLSI de NEMS et de simulation électromécanique de ces éléments. Le premier but de la thèse est l'étude des phénomènes de bruit limitant la résolution en masse afin d'atteindre 10 Da au lieu des 1000 Da actuels sur des rangs de masses large allant de 10Da à 1MDa. Dans un second temps, La concept de spectrométrie de masse à base de NEMS est validé en comparant des spectres obtenus sur des nano-agrégats de quelques nanomètres de diamètres avec ceux fournis par un spectromètre de masse temps-de-vol conventionnel. Puis, un système d'adressage fréquentiel de réseau de NEMS est mis en place pour permettre la mesure quasi simultanée de 20 résonateurs. Enfin, le réseau de NEMS est inséré dans le banc de nano-aggrégats pour mesurer 20 spectres de masses en parallèle et valider une première preuve de concept. / The aim of the project is to bring a proof of concept of a simplified mass spectrometer architecture using an ultra dense network of NEMS in association with elements of CMOS circuit as sensors in order to amplify the signal in situ and adress them individually. Since several years, Roukes' team at Caltech has demonstrated a mass spectrometry with a NEMS. In parallel, the CEA/LETI-MINATEC has developped a fabrication approach called VLSI of NEMS and an electromecanical simulation method of these elements The first objective of this thesis is to study the noise phenomenon currently limiting our mass resolution in order to reach 10 Da instead of current 1000 Da on ranges going from 10 Da to 1MDa. In a second step, the concept of NEMS-based mass spectrometry is validated by comparison a nanometric cluster spectra with those from a conventional time-of-flight mass spectrometer. Then, a frequency addressing technique is applied on an NEMS array to allow for quasi simultaneous tracking of 20 different resonators. Finally, the NEMS array is inserted in the nanocluster bench to measure 20 spectra in parallel and validate a first proof of concept.

<p> A thin film thickness monitor has been designed and constructed based on the "mass loading" effect of a resonant quartz crystal. A 6.0 MHz Y-cut crystal, having a theoretical "mass determination sensitivity" of 8.15x10^7 Hz. - cm^2/gm, serves as the sensor element. This sensitivity can be closely approached in practice if the entire active area of the quartz plate is exposed to the evaporant stream. However, due to source, substrate and crystal geometry the "effective" sensitivity of the monitor is only 0.433 of the above value. </p> <p> Both film thickness and deposition rate can be measured by the monitor in terms of equivalent frequency changes. The actual thickness and rates depend upon the density of the evaporant. In the case of silver (density 10.5 gm/cm^3), the monitor measures average thicknesses from several (oA) to 1.36 microns in one single deposition. Each crystal can be used to monitor a total of 4.5 microns of silver before replacement. Deposition rates for silver can be measured from as low as 0.l (oA)/sec to 1360 (oA)/sec. </p> <p> By combining the thickness monitor with apparatus for controlled evaporation, a system was set up which can control film thickness to within 2% and deposition rate to within 5%. </p> / Thesis / Master of Engineering (MEngr)

The objective of this thesis is to introduce novel procedures and guidelines to design bandstop microwave filters for modern terrestrial and satellite wireless communication systems. Among all available microwave filter technologies, planar structures of microstrip and substrate integrated waveguide (SIW) are chosen, due to ease of fabrication, low profile, weight and manufacturing cost. Particularly, SIW structures are more attractive because they have a better insertion loss, quality factor, and power handling capability in comparison to their microstrip counterparts, and can also be easily integrated into other planar circuitries. A comprehensive hybrid analytic-optimization method is developed to synthesize any single-band as well as multi-band bandstop coupling matrix. In this method, the location of reflection zeros (RZs) and the attenuations in stopbands can be determined in advance. Several novel single-band, dual-band, and triple-band bandstop filters are designed using regular and ridged SIW resonators, in-line coupled singlet resonators, cross-coupled resonators, and bandstop stubs. The designed filters have fractional bandwidths up to 23% . Moreover, a tunable ridged SIW bandstop resonator and a tunable CPW resonator, etched into the top plate of the SIW transmission line, are introduced. Combining these two resonators, a dual-band SIW filter is designed that permits one of its stopband to be tuned while another stopband is fixed. All introduced filters in this thesis are verified by commercial electromagnetic software, analytic investigations using Matlab codes, and measurements. / Graduate

No description available.

Energy efficiency is a vital key component when designing and miniaturizing self sustained microsystems. The smaller the system, the smaller is the possibility to store enough stored energy for a long and continuous operational time. To move such a system in an energy efficient way, a piezoelectrical locomotion module consisting of four resonating cantilevers has been designed, manufactured and evaluated in this work. The combination of a suitable substrate, a multilayered piezoelectric material to reduce the voltage, and a resonating drive mechanism resulted in a low power demand. A manufacturing process for multilayer cantilever actuators made of P(VDF-TrFE) with aluminum electrodes on a substrate of flexible printed circuit board (FPC), has been developed. An important step in this process was the development of an etch recipe for dry etching the multilayer actuators in an inductive plasma equipment. Formulas for the quasi static tip deflection and resonance frequency of a multilayered cantilever, have been derived. Through theses, it was found that the multilayered structures should be deposited on the polymer side of the FPC in order to maximize the tip deflection. Both a large and a miniaturized locomotion module were manufactured and connected by wires to verify that the three legged motion principal worked to move the structures forward and backward, and turn it right and left. By touching and adding load, to a fourth miniaturized cantilever, its ability to act as a contact sensor and carry object was verified. The presented locomotion module is part of a multifunctional microsystem, intended to be energy efficient and powered by a solar panel with a total volume of less than 25 mm3 and weight 65 mg. The whole system, consisting of a solar cell, an infra red communication module, an integrated circuit for control, three capacitors for power regulating, the locomotion module and an FPC connecting the different modules, was surface mounted using a state of the art industrial facility. Two fully assembled systems could be programmed both through a test connector and through optical sensors in the multifunctional solar cell. One of these was folded together to the final configuration of a robot. However, the entire system could not be tested under full autonomous operating conditions. On the other hand, using wires, the locomotion module could be operated and used to move the entire system from a peak-to-peak voltage of 3.0 V.